Fluid heat exchange systems

ABSTRACT

A fluid heat exchanger includes: a heat spreader plate including an intended heat generating component contact region; a plurality of microchannels for directing heat transfer fluid over the heat spreader plate, the plurality of microchannels each having a first end and an opposite end and each of the plurality of microchannels extending substantially parallel with each other microchannel and each of the plurality of microchannels having a continuous channel flow path between their first end and their opposite end; a fluid inlet opening for the plurality of microchannels and positioned between the microchannel first and opposite ends, a first fluid outlet opening from the plurality of microchannels at each of the microchannel first ends; and an opposite fluid outlet opening from the plurality of microchannels at each of the microchannel opposite ends, the fluid inlet opening and the first and opposite fluid outlet openings providing that any flow of heat transfer fluid that passes into the plurality of microchannels, flows along the full length of each of the plurality of microchannels in two directions outwardly from the fluid inlet opening. A method of cooling a heat generating component uses a fluid heat exchanger that splits a mass flow of coolant.

RELATED APPLICATIONS

This application claims the benefit of and priority to U.S. ProvisionalPatent Application No. 60/954,987, filed on Aug. 9, 2007, pending U.S.patent application Ser. No. 12/189,476, filed on Aug. 11, 2008, and U.S.Provisional Patent Application No. 61/512,379, filed on Jul. 27, 2011,which applications are hereby incorporated by reference in theirrespective entireties, for all purposes.

BACKGROUND

The innovations and related subject matter disclosed herein(collectively referred to as the “disclosure”) generally pertain tofluid heat exchange systems. Some systems are described in relation toelectronics cooling applications by way of example, though the disclosedinnovations may be used in a variety of other applications.

Fluid heat exchangers are used to cool electronic and other devices byaccepting and dissipating thermal energy therefrom.

Fluid heat exchangers seek to dissipate to a fluid passing therethrough, thermal energy communicated to them from a heat source.

Despite the existence of many previously proposed fluid heat exchangesystems, there remains a need for heat exchange systems configured toprovide improved thermal performance. As well, there remains a need forsystems configured for existing and developing small form factors, andmore particularly. For example, there remains a need for low-profileheat exchange assemblies (e.g., integrated heat sink and pumpassemblies) having a vertical component height of about 27 mm, such asbetween about 24 mm to about 27.5 mm, or less. There also remains a needfor integrated components and systems having fewer fluid connections. Inaddition, there is a need for low-pressure-loss flow transitions inintegrated heat exchange components.

SUMMARY

The innovations disclosed herein overcome many problems in the prior artand address the aforementioned, as well as other, needs. The innovationsdisclosed herein pertain generally to fluid heat exchange systems andmore particularly, but not exclusively, to approaches for integratingcomponents in such systems. For example, some innovations are directedto low-profile pump housings. Other innovations are directed to heatsink designs that deliver improved heat-transfer and/or pressure-lossperformance. And other innovations are directed to approaches foreliminating system components while retaining their respectivefunctions.

In accordance with a broad aspect of the innovations disclosed herein,there is provided a fluid heat exchanger comprising: a heat spreaderplate including an intended heat generating component contact region; aplurality of microchannels for directing heat transfer fluid over theheat spreader plate, the plurality of microchannels each having a firstend and an opposite end and each of the plurality of microchannelsextending substantially parallel with each other microchannel and eachof the plurality of microchannels having a continuous channel flow pathbetween their first end and their opposite end; a fluid inlet openingfor the plurality of microchannels and positioned between themicrochannel first and opposite ends, a first fluid outlet opening fromthe plurality of microchannels at each of the microchannel first ends;and an opposite fluid outlet opening from the plurality of microchannelsat each of the microchannel opposite ends, the fluid inlet opening andthe first and opposite fluid outlet openings providing that any flow ofheat transfer fluid that passes into the plurality of microchannels,flows along the full length of each of the plurality of microchannels intwo directions outwardly from the fluid inlet opening.

In accordance with another broad aspect of the disclosed innovations,there is provided a method for cooling a heat generating componentcomprising: providing a fluid heat exchanger including a heat spreaderplate; a plurality of microchannels for directing heat transfer fluidover the heat spreader plate, the plurality of microchannels each havinga first end and an opposite end and each of the plurality ofmicrochannels having a continuous channel flow path between their firstends and their opposite ends; a fluid inlet opening for the plurality ofmicrochannels and positioned between the microchannel first and oppositeends, a first fluid outlet opening from the plurality of microchannelsat each of the microchannel first ends; and an opposite fluid outletopening from the plurality of microchannels at each of the microchannelopposite ends; mounting the heat spreader plate onto the heat generatingcomponent creating a heat generating component contact region where theheat generating component contacts the heat spreader plate; introducinga flow of heat exchanging fluid to the fluid heat exchanger; urging theflow of heat exchanging fluid through the fluid inlet into the pluralityof microchannels first to a microchannel region between the ends of themicrochannel; and, diverting the flow of heat exchanging fluid into aplurality of subflows that each flow away from the other, a first of theplurality of subflows flowing from the fluid inlet toward the firstfluid outlet and a second of the plurality of subflows flowing from thefluid inlet toward the opposite fluid outlet.

According to another broad aspect of the disclosed innovations, heatexchange systems are disclosed.

Some described heat exchange systems have a heat sink with a pluralityof juxtaposed fins defining a corresponding plurality of microchannelsbetween adjacent fins, and a recessed groove extending transverselyrelative to the fins. A manifold body at least partially defines anopening generally overlying the groove.

The manifold body and the groove can together define a portion of aninlet manifold. The inlet manifold can be configured to hydraulicallycouple in parallel each of the microchannels to at least one other ofthe microchannels.

The heat sink can have a heat spreader, with each of the fins extendingfrom the heat spreader. The fins and the heat spreader can form aunitary construction, in some heat sink embodiments. Each of the finscan define a corresponding distal edge spaced from the heat spreader,and the groove can be recessed from the respective plurality of distaledges. In some heat sink embodiments, a lowermost extent of the recessedgroove is spaced from the heat spreader. In other heat sink embodiments,a lowermost extent of the recessed groove is substantially coextensivewith the heat spreader. As described below, each of the respectivedistal edges can define a corresponding recessed portion, therebydefining the recessed groove.

In some embodiments, the recessed groove comprises a first groovepositioned adjacent a first end of the fins and a second groovepositioned adjacent a second, opposing end of the fins. For example, thefirst groove and the second groove can define respective portions of anexhaust manifold.

The cross-sectional profile of the recessed groove can have any of avariety of shapes. For example, in some heat sink embodiments, across-sectional profile of the recessed groove comprises a selected oneor more of the group consisting of a v-shaped notch, a semi-circle, aparabola, a hyperbola, and a notch having at least one substantiallystraight edge.

In some heat sink embodiments, a ratio of a representative height of theplurality of fins to a representative depth of the groove is betweenabout 10:1 and about 10:7. For example, the ratio of the representativeheight to the representative depth can be between about 3:1 and about2:1.

The opening in the manifold body can have a recessed region and anaperture extending through the manifold body from the recessed region.In some instances, the recessed region in the manifold body is a taperedrecessed region having at least one cross-sectional dimension thatdiminishes with increasing depth of the recessed region. A slope of therecessed groove adjacent the manifold body can be substantiallycontinuous with a slope of the recessed region in the manifold bodyadjacent the groove. The recessed region, the aperture and the groovecan together define a flow transition having a characteristic lengthscale between about 150% and about 200% greater than a correspondingcharacteristic length scale of the aperture.

In some heat exchange systems of the type described herein, the inletmanifold can be configured to deliver a flow of a fluid to each of themicrochannels in a transverse direction relative to a longitudinal axisof the respective microchannels. Some heat exchange systems have q bodydefining an inlet plenum. The inlet plenum and the inlet manifold cantogether be configured to deliver a fluid flow to in a directiongenerally transverse to the fins. For example, the inlet manifold can beconfigured to deliver an impingement flow of the fluid to each of themicrochannels.

In some heat sink embodiments, each of the fins in the plurality of finsdefines a corresponding beveled distal edge.

Some heat exchange systems also have a unitary body defining a firstside and a second side positioned opposite the first side. A portion ofthe inlet plenum and a portion of the inlet manifold can be respectivelyrecessed from the first side. A recess from the second side can define apump volute, and the portion of the inlet plenum recessed from the firstside can be positioned adjacent the pump volute. The recess defining thepump volute can be a substantially cylindrically-shaped recess having alongitudinal axis extending substantially perpendicularly to the secondside. The unitary body can define an opening extending generallytangentially of the cylindrically-shaped recess and hydraulically couplethe pump volute to the inlet plenum.

The body can define a second recessed region adjacent the inlet manifoldrecess and a wall separating the second recessed region from the inletmanifold recess. The manifold body can be configured to straddle theinlet manifold recess and matingly engage the body such that themanifold body so occupies a portion of the second recessed region as todefine an exhaust manifold that generally overlies a respective portionof each of the microchannels. The respective portions of the pluralityof microchannels can be spaced from the inlet manifold.

In accordance with yet another broad aspect of the disclosedinnovations, some described heat exchange systems have a heat sink witha plurality of juxtaposed fins defining a corresponding plurality ofmicrochannels between adjacent fins. Each of the fins can define arespective beveled distal edge. A manifold body can overlie at least aportion of each of the beveled distal edges and define an openingconfigured to deliver a flow of fluid to the microchannels in adirection transverse to the microchannels.

A distance between a respective beveled distal edge and the heatspreader can define a height of the respective fin. Each respective fincan define a first end and a second end, and extend longitudinally in aspanwise direction relative to the heat spreader between the first andthe second end. The respective fin height of one or more of theplurality of fins can vary along the spanwise direction. The manifoldbody can have a compliant portion urging against at least a portion ofeach of the distal edges. For example, the variation in fin height alongthe spanwise direction can define a non-linear contour of the respectivedistal edge, and the compliant portion of the manifold body cangenerally conform to the non-linear contour.

A recessed groove can extend transversely relative to the fins and theopening can generally overlie the groove. Each of the respective distaledges can define a corresponding recessed portion, thereby defining therecessed groove.

A ratio of a representative height of the plurality of fins to arepresentative depth of the groove can be between about 10:1 and about10:7. For example, the ratio of the representative height to therepresentative depth can be between about 3:1 and about 2:1.

According to another broad aspect of the disclosed innovations, unitaryconstructs are described. For example, a unitary construct can have afirst side, a second side positioned opposite the first side, and asubstantially continuous perimeter wall extending between the first sideand the second side. A floor can generally separate the first side fromthe second side. The first side can define a substantiallycylindrically-shaped recess and the second side can define a recesshaving a region positioned radially outward of the substantiallycylindrically-shaped recess defined by the first side.

In some instances, the unitary construct can define an apertureextending between the substantially cylindrically-shaped recess and theportion of the recess from the second side positioned radially outwardof the substantially cylindrically-shaped recess.

The perimeter wall can define one or more perimeter recesses. Theconstruct can define an aperture in the floor extending between one ofthe perimeter recesses and the substantially cylindrically-shapedrecess. The construct can define an aperture extending between one ofthe perimeter recesses and the recess defined by the second side. Theconstruct can define an aperture extending between one of the perimeterrecesses and the portion of the recess from the second side positionedradially outward of the substantially cylindrically-shaped recess.

The one or more perimeter recesses can include a first perimeter recessand a second perimeter recess. The construct can define an apertureextending between the second perimeter recess and the recess defined bythe second side. The perimeter wall can also define a third perimeterrecess and the construct can define an aperture extending between thethird perimeter recess and the portion of the recess from the secondside positioned radially outward of the substantiallycylindrically-shaped recess.

Some embodiments of the construct generally define a housing. Thesubstantially cylindrically-shaped recess can define a pump volute, andthe recess from the second side can define a plenum. The plenum can be aheat sink inlet plenum defined by the portion of the recess from thesecond side positioned radially outward of the substantiallycylindrically-shaped recess. The recess from the second side can definea portion of a heat-sink inlet manifold, a portion of a heat-sink outletmanifold, and a portion of a heat-sink outlet manifold.

It is to be understood that other innovative aspects will become readilyapparent to those skilled in the art from the following detaileddescription, wherein various embodiments are shown and described by wayof illustration. As will be realized, other and different embodimentsare possible and several details are capable of modification in variousother respects, all without departing from the spirit and scope of theprinciples disclosed herein.

Accordingly the drawings and detailed description are to be regarded asillustrative in nature and not as restrictive.

BRIEF DESCRIPTION OF THE DRAWINGS

Unless specified otherwise, the accompanying drawings illustrate aspectsof the innovative subject matter described herein. Referring to thedrawings, wherein like reference numerals indicate similar partsthroughout the several views, several aspects of the presently disclosedprinciples are illustrated by way of example, and not by way oflimitation, in detail in the drawings, wherein:

FIG. 1 shows a fluid circuit configured to transfer heat from one regionto another with a circulatable working fluid.

FIG. 2 shows a top plan view of a fluid heat exchanger having a top capcut away to facilitate viewing internal components;

FIG. 3 shows a sectional view along line I-I of FIG. 2;

FIG. 4 shows a sectional view along line II-II of FIG. 3;

FIG. 5 shows an exploded, perspective view of another fluid heatexchanger;

FIG. 6 shows a top plan view of the fluid heat exchanger shown in FIG. 5assembled with its top cap removed;

FIG. 7 illustrates an exploded view of an embodiment of an integratedpump and heat exchanger assembly.

FIG. 8 illustrates an isometric view of an exploded subassembly of theintegrated housing and pump impeller shown in FIG. 7.

FIG. 9 illustrates a partial cross-sectional view from above theintegrated housing shown in FIGS. 7 and 8.

FIG. 10 illustrates an isometric view from below of the integratedhousing shown in FIGS. 7, 8 and 9 with a flow path of a fluid shown as adashed line.

FIG. 11 illustrates an exploded view of a subassembly comprising theheat sink, the integrated housing and the manifold insert shown in FIG.7.

FIG. 12 illustrates an isometric view from above the insert shown inFIGS. 7 and 11.

FIG. 13 illustrates an isometric view of a heat sink as shown in FIG. 7.

FIG. 13A shows a magnified view of a portion of the heat sink shown inFIG. 13.

FIG. 14 illustrates an isometric view of another embodiment of a heatsink shown in FIG. 7.

FIG. 14A shows a magnified view of a portion of the heat sink shown inFIG. 14.

FIG. 15 illustrates a typical cross-sectional view of a heat sink asshown in FIG. 7, e.g., as taken along Section 15-15 in FIG. 13 or inFIG. 14.

FIG. 16 illustrates an example of beveled fins.

FIG. 17 illustrates an example of blunt fins.

FIG. 18A illustrates a cross-sectional view of a heat sink having av-shaped, transverse groove in its fins as taken along section line18-18 in FIG. 14.

FIG. 18B illustrates a cross-sectional view of a heat sink having agenerally parabolic, transverse groove in its fins as taken alongsection line 18-18 in FIG. 14.

FIG. 19 illustrates a cross-sectional view of a heat sink as shown inFIG. 18A with the manifold insert shown in FIG. 12 overlying the fins ofthe heat sink.

FIG. 19A illustrates a cross-sectional view of a heat sink as shown inFIG. 18A having the manifold insert shown in FIG. 12 overlying the finsof the heat sink.

FIG. 19B illustrates another cross-sectional view of a heat sinkdefining a transverse groove and having the manifold insert shown inFIG. 12 overlying the fins.

DETAILED DESCRIPTION

The following describes various innovative principles related to heatexchange systems by way of reference to specific examples. However, oneor more of the disclosed principles can be incorporated in varioussystem configurations to achieve any of a variety of correspondingsystem characteristics. The detailed description set forth below inconnection with the appended drawings is intended as a description ofvarious embodiments and is not intended to represent the onlyembodiments contemplated by the inventor. The detailed descriptionincludes specific details for the purpose of providing a comprehensiveunderstanding of the principles disclosed herein. However, it will beapparent to those skilled in the art after reviewing this disclosurethat one or more of the claimed inventions may be practiced without oneor more of the illustrated details.

Stated differently, systems described in relation to particularconfigurations, applications, or uses, are merely examples of systemsincorporating one or more of the innovative principles disclosed hereinand are used to illustrate one or more innovative aspects of thedisclosed principles. Thus, heat exchange systems having attributes thatare different from those specific examples discussed herein can embodyone or more of the innovative principles, and can be used inapplications not described herein in detail, for example to transferheat to or from components in a data center, laser components,light-emitting diodes, chemical reactions, photovoltaic cells, solarcollectors, electronic components, power electronics, opto-electronics(e.g., used in switches) and a variety of other industrial, military andconsumer devices now known or hereafter developed. Accordingly, suchalternative embodiments also fall within the scope of this disclosure.

Fluid Circuit

The schematic illustration in FIG. 1 shows several functional featurescommon among disclosed fluid-based heat exchanger systems. For example,the fluid circuit 10 has a first heat exchanger 11 configured to absorbheat from a heat source (not shown in FIG. 1) and a second heatexchanger 12 configured to reject heat from the circuit 10. As indicatedin FIG. 1, a working fluid, or coolant, can circulate between the heatexchangers 11, 12 to carry the energy absorbed by the working fluid inthe first heat exchanger to the second heat exchanger 12 where energycan be rejected from the fluid. One or both of the heat exchangers 11,12 can be a microchannel heat exchanger.

As used herein, “microchannel” means a fluid conduit, or channel, havingat least one major dimension (e.g., a channel width) measuring less thanabout 1 mm, such as, for example, about 0.1 mm, or several tenths ofmillimeters.

As used herein, “fluidic” means of or pertaining to a fluid (e.g., agas, a liquid, a mixture of a liquid phase and a gas phase, etc.). Thus,two regions that are “fluidicly coupled” are so coupled to each other asto permit a fluid to flow from one of the regions to the other region inresponse to a pressure gradient between the regions.

As used herein, the terms “working fluid” and “coolant” areinterchangeable. Although many formulations of working fluids arepossible, common formulations include distilled water, ethylene glycol,propylene glycol, and mixtures thereof.

As used herein, the terms “heat sink” and “heat exchanger” areinterchangeable and mean a device configured to transfer energy to orfrom a fluid through convection (i.e., a combination of conduction andadvection) heat transfer.

Referring again to FIG. 1, the working fluid typically enters a firstmanifold 13 (sometimes after passing through an inlet plenum, which isomitted from FIG. 1 for ease of illustration). From the manifold 13, thefluid can be distributed among a plurality of fluid passages 14configured to transfer heat from a heat-transfer surface, e.g., a wallin the heat exchanger 11, to the working fluid. In some embodiments,such as the examples described below, the fluid passages 14 areconfigured as microchannels and the walls are configured as extendedheat-transfer surfaces, or fins.

During operation of the circuit 10, energy conducts (e.g., diffuses)from the walls of the first heat exchanger into adjacent fluid particleswithin the passages 14, and the adjacent fluid particles are swept awayfrom the wall, or advected, carrying the energy absorbed from the walls.The swept-away particles are replaced by other, usually cooler fluidparticles, which more readily absorb energy from the walls (e.g., byvirtue of their usually lower temperature). Such a combination ofconduction and advection (i.e., convection) provides an efficientapproach for cooling devices having a relatively high heat flux, suchas, for example, electronic devices.

After passing through the plurality of passages 14 in the first heatexchanger 11, the heated working fluid collects in an exhaust manifold15 and passes to the second heat exchanger 12, carrying with it theenergy absorbed from the first heat exchanger 11. As the heated fluidpasses through the second heat exchanger 12, energy is rejected from thefluid (e.g., to another working fluid, such as, for example, the air ora building's water supply) through convection processes similar to thosedescribed above. From the second heat exchanger, the cooled workingfluid passes through a pump 16 and back to the first heat exchanger 11.

The dashed box in FIG. 1 indicates that several functional components ofthe circuit 10 can be integrated into a single subassembly. As anexample, the subassembly 20 includes the pump 16, the manifolds 13, 15and the passages 14, as well as, for example, conduits between the pumpand the manifold 13. An inlet 21 and an outlet 22 operatively couple thesubassembly 20 to the second heat exchanger 12. A working embodiment ofsuch a subassembly 20 is described below in connection with FIG. 7, etseq.

Each of the innovative features described herein can be incorporated,either singly or in combination, in connection with the first heatexchanger 11, the second heat exchanger 12, or both.

Heat Exchanger Example

With reference to FIGS. 2 to 4, a fluid heat exchanger 100 is shown.Fluid heat exchanger 100 includes a heat spreader plate 102, anarrangement of fluid microchannels 103 defined between walls 110, afluid inlet passage 104, and a fluid outlet passage 106. A housing 109operates with heat spreader plate 102 to form an outer limit of the heatsink and to define fluid flow passages 104, 106.

As shown in FIGS. 3 and 4, in use the heat exchanger 100 is coupled to aheat source 107, such as an electronic device, including, but notlimited to a microchip or an integrated circuit. The heat exchanger maybe thermally coupled to the heat source by a thermal interface materialdisposed therebetween, by coupling directly to the surface of the heatsource, or by integrally forming the heat source and at least the heatspreader plate 102 of the fluid heat exchanger. The heat exchanger 100may take various forms and shapes, but heat spreader plate 102 is formedto accept thermal energy from heat source 107. Heat spreader plate 102includes an intended heat generating component contact region 102 bpositioned in a known location thereon. In the illustrated embodiment,heat spreader plate 102 includes a protrusion at region 102 b thatcontrols the positioning of the heat spreader plate relative to the heatsource, but such a protrusion need not be included. Heat spreader plate102 may include a portion of more conductive material to facilitate andcontrol heat transfer, if desired. In any event, heat spreader plate isformed to fit over and thermally communicate with a heat source in aregion 102 b, usually located centrally relative to the edges of theheat spreader plate.

Microchannels 103 are formed to accept and allow passage therethrough ofthe flow of heat exchanging fluid such that the fluid can move alongheat spreader plate 102 and walls 110 and accept and dissipate heatenergy from them. In the illustrated embodiment, microchannels 103 aredefined by walls 110 that are thermally coupled to the heat spreaderplate to accept thermal energy therefrom. For example, heat spreaderplate 102 may include an inner facing, upper surface 102 a and aplurality of microchannel walls 110 may extend upwardly therefrom,whereby the channel area, defined between upper surface 102 a and themicrochannel walls 110, channels or directs fluid to create a fluid flowpath. The channel area may be open or filled with thermally conductiveporous material such as metal or silicon foam, sintered metal, etc.Thermally conductive, porous materials allow flow through the channelsbut create a tortuous flow path.

Surface 102 a and microchannel walls 110 allow the fluid to undergoexchange of thermal energy from the heat spreader plate to cool the heatsource coupled to the heat spreader plate. The upper surface 102 a andwalls 110 have a high thermal conductivity to allow heat transfer fromthe heat source 107 to fluid passing through channels 103. The surfacesforming channels 103 may be smooth and solid, formed with a porousstructure, such as of sintered metal and/or metal or silicon foam orroughened, for example, including troughs and/or crests designed tocollect or repel fluid from a particular location or to create selectedfluid flow properties. Facing microchannel walls 110 may be configuredin a parallel configuration, as shown, or may be formed otherwise,provided fluid can flow between the microchannel walls 110 along a fluidpath. It will be apparent to one skilled in the art that themicrochannel walls 110 may be alternatively configured in any otherappropriate configuration depending on various factors of desired flow,thermal exchange, etc. For instance, grooves may be formed betweensections of microchannel walls 110. Generally, microchannel walls 110may desirably have dimensions and properties which seek to reduce orpossibly minimize the pressure drop or differential of fluid flowingthrough the channels 103 defined therebetween.

The microchannel walls 110 may have a width dimension within the rangeof 20 microns to 1 millimeter and a height dimension within the range of100 microns to five millimeters, depending on the power of the heatsource 107, desired cooling effect, etc. The microchannel walls 110 mayhave a length dimension which ranges between 100 microns and severalcentimeters, depending on the dimensions of, and the heat flux densityfrom, the heat source. In one embodiment, the walls 110 extend the fulllength (which may be a width) dimension of the heat spreader platepassing fully through region 102 b. These are exemplary dimensions and,of course, other microchannel wall dimensions are possible. Themicrochannel walls 110 may be spaced apart by a separation dimensionrange of 20 microns to 1 millimeter, depending on the power of the heatsource 107, although other separation dimensions are contemplated.

Other microporous channel configurations may be used alternatively to,or together with, microchannels, such as for example, a series ofpillars, fins, or undulations, etc. which extend upwards from the heatspreader plate upper surface or tortuous channels as formed by a foam orsintered surface.

Fluid heat exchanger 100 further includes a fluid inlet passage 104,which in the illustrated embodiment includes a port 111 through thehousing opening to a header 112 and thereafter a fluid inlet opening 114to the microporous fluid channels 103.

Fluid Distribution

The port and the header can be formed in various ways andconfigurations. For example, port 111 may be positioned on top, asshown, side or end regions of the heat exchanger, as desired. Port 111and header 112 are generally of a larger cross sectional area thanopening 114, so that a mass flow of fluid can be communicatedsubstantially without restriction to opening 114.

Although only a single fluid inlet opening 114 is shown, there may beone or more fluid inlet openings providing communication from the headerto the fluid microchannels 103.

Fluid inlet opening 114 may open to microchannels 103 opposite the heatspreader plate such that fluid passing through the opening may passbetween walls 110 toward surface 102 a, before being diverted along theaxial length of the channels, which extend parallel to axis x. Sincemost installations will position the heat spreader plate as thelowermost, as determined by gravity, component of heat exchanger 100,the fluid inlet openings 114 can generally be described as beingpositioned above the microchannels 103 such that fluid may flow throughopening 114 down into the channels in a direction orthogonal relative tothe plane of surface 102 a and towards surface 102 a and then changedirection to pass along the lengths of channels 103 substantiallyparallel to surface 102 a and axis x. Such direction change is driven byimpingement of fluid against surface 102 a.

Fluid inlet opening 114 may be positioned adjacent to the known intendedheat generating component contact region 102 b since this region of theheat spreader plate may be exposed to greater inputs of thermal energythan other regions on plate 102. Positioning the fluid inlet openingadjacent region 102 b seeks to introduce fresh heat exchanging fluidfirst and directly to the hottest region of the heat exchanger. Theposition, arrangement and/or dimensions of opening 114 may be determinedwith consideration of the position of region 102 b such that opening 114may be placed adjacent, for example orthogonally opposite to, oraccording to the usual mounting configuration above, the intended heatgenerating component contact region 102 b on the heat plate. Thedelivery of fresh fluid first to the region that is in directcommunication with the heat generating component to be cooled seeks tocreate a uniform temperature at the contact region as well as areas inthe heat spreader plate away from the contact region.

In the illustrated embodiment, opening 114 is positioned to have itsgeometric center aligned over the center, for example the geometriccenter, of region 102 b. It is noted that it may facilitate constructionand installation by intending, and possibly forming, the heat sinkspreader plate to be installed with the heat generating componentpositioned on the plate substantially centrally, with respect to theplate's perimeter edges, and then opening 114 may be positioned alsowith its geometric center substantially centrally with respect to theperimeter edges of the heat spreader plate. In this way, the geometriccenter points of each of opening 114, the heat spreader plate and theheat generating component may all be substantially aligned, as at C.

Opening 114 may extend over any channel 103 through which it is desiredthat heat exchange fluid flows. Openings 114 may take various formsincluding, for example, various shapes, various widths, straight orcurved edges (in plane or in section) to provide fluid flow features,open area, etc., as desired.

Heat exchanger 100 further includes a fluid outlet passage 106, which inthe illustrated embodiment includes one or more fluid outlet openings124 from the microporous fluid channels 103, a header 126 and an outletport 128 opening from the housing. Although two fluid outlet openings124 are shown, there may be one or more fluid outlet openings providingcommunication to the header from the fluid channels 103.

The port and the header can be formed in various ways andconfigurations. For example, port 128 may be positioned on top, asshown, side or end regions of the heat exchanger, as desired.

Fluid outlet openings 124 may be positioned at the end of microchannels103. Alternately or in addition, as shown, fluid outlet openings 124 maycreate an opening opposite heat spreader plate 102 such that fluidpassing through the channels pass axially along the length of thechannels between walls 110 and then changes direction to pass away fromsurface 102 a out from between the walls 110 to exit through openings124. Since most installations will position the heat spreader plate asthe lowermost, as determined by gravity, component of heat exchanger100, the fluid outlet openings 124 will generally be positioned abovethe microchannels 103 such that fluid may flow from the channelsupwardly through openings 124.

Fluid outlet openings 124 may be spaced from fluid inlet openings 114 sothat fluid is forced to pass through at least a portion of the length ofchannels 103 where heat exchange occurs before exiting themicrochannels. Generally, fluid outlet openings 124 may be spaced fromthe known intended heat generating component contact region 102 b.

In the illustrated embodiment, where heat exchanger 100 is intended tobe mounted with heat source 107 generally centrally positioned relativeto the perimeter edges of heat spreader plate 102, and thereby the ends103 a of channels, openings 124 may be positioned at or adjacent channelends 103 a.

At least one opening 124 extends over any channel 103 through which itis desired that heat exchange fluid flows. Openings 124 may take variousforms including, for example, various shapes, various widths, straightor curved edges (in plane or in section) to provide fluid flow features,open area, etc. as desired.

Fluid inlet opening 114 may open away from the ends of themicrochannels, for example along a length of a microchannel between itsends. In this way, fluid is introduced to a middle region of acontinuous channel 103 rather than fluid being introduced to one end ofa channel and allowing it to flow the entire length of the channel. Inthe illustrated embodiment, heat exchanger 100 is intended to be mountedwith heat source 107 generally centrally positioned relative to theperimeter edges of heat spreader plate 102. As such, in the illustratedembodiment, opening 114 is positioned generally centrally relative tothe edges of the heat plate 102. Since the channels, in the illustratedembodiment extend substantially continuously along the length of theheat plate between opposing side perimeter edges thereof, opening 114opens generally centrally between ends 103 a of each channel. Forexample, opening 114 may be positioned in the middle 50% of the heatexchanger or possibly the middle 20% of the heat exchanger. The deliveryof fresh fluid to the central region where the heat generating componentis in direct communication with the heat spreader plate, first beforepassing through the remaining lengths of channels seeks to create auniform temperature at region 102 b as well as areas in the heatspreader plate adjacent to the intended mounting position. Theintroduction of fluid to a region along a middle region of themicrochannels after which the flow splits into two sub flows to passoutwardly from the inlet towards a pair of outlets, each of which ispositioned at the ends of the channels reduces the pressure drop offluid passing along the channels over that pressure drop that would becreated if the fluid passed along the entire length of each channel.Splitting the fluid flow to allow only approximately one half of themass inlet flow to pass along any particular region of the microchannelscreates less back pressure and less flow resistance, allows faster fluidflow through the channels and lessens the pump force required to movethe fluid through the heat exchanger.

In use, heat spreader plate 102 is positioned in thermal communicationwith heat source 107 at region 102 b. Heat generated by heat source 107is conducted up through heat spreader plate 102 to surface 102 a andwalls 110. Heat exchanging fluid, as shown by arrows F, enters the fluidheat exchanger through port 111, passes into the header 112 and throughopening 114. The heat exchanging fluid then passes down between walls110 into channels 103, where the fluid accepts thermal energy from thewalls 110 and surface 102 a. The heat exchanging fluid, after passingdown into the channels, then impinges against surface 102 a to bediverted toward ends 103 a of the channels toward outlet openings 124.In so doing, in the illustrated embodiment, the fluid is generally splitinto two subflows moving away from each other and away from inlet 114toward openings 124 at the ends of the microchannels. Fluid passingthrough channels becomes heated, especially when passing over the regionin direct contact with the heat source, such as, in the illustratedembodiment, the central region of the heat spreader plate. Heated fluidpasses out of openings 124, into header and thereafter through port 128.The heated fluid will circulate through a heat sink where its thermalenergy is unloaded before circulating back to port 111.

The individual and relative positioning and sizing of openings 114 and124 may allow fluid to circulate through the heat exchanging channels103 while reducing the pressure drop generated in fluid passing throughheat exchanger 100, when compared to other positionings and sizings. Inthe illustrated embodiment, for example, the central region 124 a ofoutlet openings 124 are scalloped to offer an enlarged outlet regionfrom the centrally located channels, relative to those on the edges.This shaping provides that the outlet openings from some centrallypositioned channels 103, relative to the sides of the heat exchanger,are larger than the outlet openings from other channels closer to theedges. This provides that fluid flowing through the more centrallylocated channels encounters less resistance to flow therethrough, againfacilitating flow past the central mounting region 102 b on heatspreader plate 102.

A seal 130 separates fluid inlet passage 104 from fluid outlet passage106 so that fluid must pass through the microporous channels 103 pastheat spreader plate surface 102 a.

Methods of Manufacture

With reference to FIGS. 5 and 6, a useful method for manufacturing afluid heat exchanger is described. A heat spreader plate 202 may beprovided which has heat conductive properties through its thickness atleast about a central region thereof.

Microchannels may be formed on the surface of the heat spreader plate,as by adding walls or forming walls by building up or removing materialsfrom the surface of the heat plate. In one embodiment, skiving is usedto form walls 210.

A plate 240 may be installed over the walls 210 to close off thechannels across the upper limits of walls 210. Plate 240 has portionsremoved to create inlet and outlet openings 214 and 224, respectively,in the final heat exchanger. Tabs 242 may be used to assist with thepositioning and installation of plate 240, wherein tabs 242 are bentdown over the two outermost walls.

Seal 230 may be installed as a portion of plate 240 or separately.

After plate 240 and seal 230 are positioned, a top cap 244 can beinstalled over the assembly. Top cap 244 can include side walls thatextend down to a position adjacent heat spreader plate. The parts may beconnected during assembly thereof or afterward by overall fusingtechniques. In so doing, the parts are connected so that shortcircuiting from inlet passage to outlet passage is substantiallyavoided, setting up the fluid circuit as described herein above whereinthe fluid flows from opening 214 to openings 224 through the channelsdefined between walls 210.

System Integration

Referring now to FIG. 7, a working example of an integrated subassembly20 (FIG. 1) is described. The illustrated subassembly 300 comprises apump 310 (e.g., 312 and 313, exclusive of retention mechanism 302) and aheat exchanger 320, as well as housing 330 with integrated fluidconduits extending therebetween. The subassembly 300 is but one exampleof an approach for integrating several elements of the fluid circuit 10shown in FIG. 1 (e.g., the pump 16 and the first heat exchanger 11,including the inlet manifold 13, the fluid passages 14, the exhaustmanifold 15) into a single element while retaining the several elements'respective functions. The illustrated housing 330 is configured toconvey a working fluid from an inlet port 331 to a pump volute 311, fromthe pump volute to an inlet 321 (FIG. 11) to the heat exchanger 320, andfrom an outlet 322 (FIG. 11) of the heat exchanger to an outlet port332.

The pump impeller 312 can be received in the pump volute 311. Theimpeller can be driven in rotation by an electric motor 313 in aconventional manner. A cap 301 can overlie the motor 313 and fasten tothe housing 330 to provide the subassembly 300 with a finishedappearance suitable for use with, for example, consumer electronics.

The side 333 of the housing 330 positioned opposite the pump volute 311can receive an insert 334 and the heat exchanger 320. A seal (e.g., anO-ring) 323 can be positioned between the housing 330 and the heatexchanger 320 to reduce and/or eliminate leakage of the working fluidfrom the interface between the heat exchanger 320 and the housing 330.

The heat exchanger 320 defines a lower-most face of the assembly 300, aswell as a surface configured to thermally couple to an integratedcircuit (IC) package (not shown). A retention mechanism 302 canmechanically couple the assembly to a substrate, such as a printedcircuit board to which the IC package is assembled.

As with the subassembly 20 shown in FIG. 1, a fluid conduit, or otherfluid coupler, can fluidicly couple an outlet port of a remotelypositioned heat exchanger to the inlet port 331 of the housing 330. Aswell, a fluid conduit, or other fluid coupler, can fluidicly couple theoutlet port 332 of the housing 330 to an inlet port of the remotelypositioned heat exchanger. In a cooling application, the respectivefluid conduits convey relatively higher-temperature fluid from theoutlet port 332 to the remote heat exchanger and relativelylower-temperature fluid from the remote heat exchanger to the inlet port331.

Integrated Housing

An embodiment of a unitary housing 330 is now described by way ofreference to FIGS. 7, 8, 9, 10 and 11. The illustrated housing 330 has afirst side 340, a second side 333 positioned opposite the first side,and a substantially continuous perimeter wall 348 extending between thefirst side and the second side. A floor, or lower wall, 341 (FIG. 9)generally separates the first side from the second side. The opposedfirst side 340 and second side 333 define respective recessed featuresthat, when combined with corresponding components, define integratedfluid conduits and chambers operable to convey a working fluid within asmall form factor (e.g., within a volume having a maximum verticaldimension of less than about 1.5 inches, such as, for example, betweenabout 0.75 inches and about 1.4 inches).

For example, the housing has an inlet port 331, a pump volute 311, aninlet plenum 335 (FIG. 10), an inlet manifold portion 336 correspondingto the inlet plenum, an exhaust manifold portion 337, an exhaust (oroutlet) plenum 338 corresponding to the exhaust manifold portion, and anoutlet port 332 fluidicly coupled with each other.

FIGS. 8 and 9 show that the perimeter wall can define a recessed inletport 331. The first side 340 of the housing 330 defines a substantiallycylindrically-shaped recess forming the pump volute 311, and a floor ofthe recessed volute 311 is defined by a substantially circular lowerwall 341. An aperture 342 in the lower wall forms an inlet to the pumpvolute 311 from the inlet port, with an inlet passage 343 extendingbetween the inlet port 331 and the inlet 342 to the pump volute 311,fluidicly coupling the pump volute and the inlet port to each other.

The opposite (e.g., a second) side 333 of the housing 330 defines asecond recessed region 350 defining the inlet (e.g., first) plenum 335and the inlet manifold region 336. An opening 344 extends through acommon wall 345 separating the inlet plenum 335 from the pump volute 311(not shown in FIG. 10), fluidicly coupling the pump volute and the firstplenum with each other. In some embodiments, the opening 344 extendsgenerally tangentially of the cylindrically-shaped pump volute 311.

A charge port 349 can extend through the perimeter wall 348 and into theinlet plenum 335, allowing an assembled system to be charged with aworking fluid after assembly is complete. After charging, a plug (notshown) can be inserted into the charge port 349 to seal it.

As shown in FIG. 10, a depth of the inlet manifold 336 can taper from arelatively deeper region adjacent the inlet plenum 335 to a relativelyshallower region spaced from the inlet plenum. As shown in FIG. 11 anddescribed more fully below, a manifold insert 334 can be positionedadjacent, e.g., “overlie”, as shown in FIG. 7, the sloped recess of themanifold region 336, at least partially forming an inlet manifold to theheat sink 320 and having a tapering cross-sectional area along a flowdirection. The tapered manifold can distribute a substantially evenmass-flow rate of working fluid among a plurality of channels in theheat sink 320.

The second side 333 of the housing 330 can define a third recessedregion 351 (FIG. 10) defining respective portions of an exhaust manifold337 (FIG. 11). As described more fully below, the third recessed region351 can overlie a portion of the heat exchanger 320 and thereby receivea discharged working fluid from the microchannels.

A fourth recessed region 352 (FIG. 10) can define, at least in part, anoutlet plenum 338. The third recess 351 and the fourth recess 352 can befluidicly coupled to each other and separated by a wall 346 from thesecond recessed region 350. An opening 347 (FIG. 9) can extend betweenthe outlet plenum 338 and the outlet port 332.

A manifold housing, or integrated housing, as described above can have aunitary construction formed using, for example, an injection moldingtechnique, a machining technique, or other suitable process now known orhereafter developed. Also, any suitable material can be used in theconstruction of the housing, provided that the material is compatiblewith other components of the subassembly 300 and the working fluid. Forexample, common materials from which an injection-molded housing can beformed include polyphenylene sulfide (commonly referred to as “PPS”),polytetrafluoroethylene (commonly referred to as “PTFE” or the tradename TEFLON by the DuPont Company), and acrylonitrile butadiene styrene(commonly referred to as “ABS”).

Although the housing described above has a unitary construction, otherembodiments of the housing 330 can comprise an assembly ofsubcomponents. Nonetheless, a unitary construction typically has fewerseparable couplings from which a working fluid can leak.

Manifold Insert

As noted above and shown in FIGS. 7 and 11, an insert 334 can bepositioned between the heat exchanger 320 and the housing 330.Additionally, the insert 334 can have a contour generally correspondingto the configuration of one or more of the recessed regions 350, 351,352 in the second side 333 of the housing 330. When the insert 334 ismated with the housing 330, the recessed regions 350, 351 and 352, incombination with the contoured insert 334, can define several conduits,or fluid couplers, suitable for conveying a working fluid so as tofluidicly couple the heat exchanger 320 with the pump volute 311 and theoutlet port 332.

For example, the insert 334 can define an opening extending through thebody 360 and generally overlying the tapered manifold portion 336defined by the housing 330. The opening can include a recessed region365 and an aperture 361. The recessed region 365 and the tapered recess336 in the housing together define a chamber of the inlet manifold. Asdescribed below, the manifold can distribute working fluid among theseveral microchannels within the heat sink.

The body 360 of the insert 334 can matingly engage with one or morefeatures of the housing 330. For example, the body 360 can define aplurality of spaced apart members 362 a, b, c, d and a trough-shapedrecess 363 extending transversely relative to the aperture 361. Thetrough-shaped recess 363 can extend between the members 362 a, c andbetween the members 362 b, d. When the insert 334 is assembled with thehousing 330, the members 362 a, b, c, d are positioned in correspondingportions of the second recessed region 351, and a corresponding ridge339 (FIG. 10) is positioned within the trough-shaped recess 363. Bystraddling features defined by the housing, the insert is configured toalign the aperture 361 with the tapered manifold region 336 in agenerally repeatable fashion.

The insert body 360 also defines a contoured tab 364 configured tooverly the recessed inlet plenum 335. In addition, a shoulder 366 withinthe second recessed region 365 of the insert urges against the wall 346(FIG. 10), providing a seal separating the inlet manifold from theexhaust manifold and outlet plenum.

In a working embodiment, the recessed region 365 (FIG. 19) is tapered,having at least one cross-sectional dimension that diminishes withincreasing depth of the recess. As explained more fully below, therecess 365 and the aperture 361 in the insert can generally overlie agroove 325 (FIG. 19) in the heat sink fins. In some instances, a slopeof a wall defining the tapered recess 365 adjacent the aperture 361 canbe matched to (e.g., can correspond to, or, alternatively, be the sameas) a slope of the recessed groove 325 adjacent a distal end of the heatsink fins, providing a relatively smooth and continuous flow transition.

The insert can have one or more (e.g., a pair) of generally conformable,flat surfaces 367 laterally flanking the aperture 361 (FIG. 11). Asshown in FIG. 19, the surfaces 367 can generally overlie respectiveportions of the heat exchanger 320 (e.g., the distal ends 401 of heatsink fins 400 (FIGS. 16 and 17)), defining an upper flow boundary of themicrochannels extending between adjacent fins, similar to the plate 240shown in FIGS. 5 and 6. The conformable surfaces 367 can urge againstthe respective distal ends, and conform to variations in height amongthe plurality of fins, and within a given fin (e.g., a fin having anon-linear longitudinal contour resulting from variations in fin heighth₂ (FIGS. 18A and 18B)). The conformable surfaces 367 can reduce oreliminate the need for secondary machining operations used to make therespective distal ends of the fins generally coplanar and compatiblewith, for example, a rigid plate. As well, conformable surfaces 367urging against the distal ends 401 of the fins 400 (400′) can form aseal with the fins and prevent a working fluid from bypassing thechannels defined between adjacent fins.

The insert body 360 can be formed using, for example, an injectionmolding technique, a machining technique, or other suitable process nowknown or hereafter developed. In a working embodiment, the body 360 isformed of a compliant polymeric material that generally conforms to andseals against adjacent surfaces. Any suitable material can be used toform the insert body 360, provided that the selected material iscompatible with other components of the subassembly 300 and the selectedworking fluid. For example, common materials from which the insert bodycan be formed include silicone or any other suitably compliant material.

Flow Distribution

Flow of a working fluid through the integrated assembly 300 is nowdescribed. From a remotely positioned heat exchanger (not shown), aworking fluid passes into the inlet port 331 and into the channel 343extending between the inlet port and the inlet 342 to the pump volute311. A floor 341 of the pump volute defines a wall separating thechannel 343 from the pump volute. From the channel 343, the workingfluid passes through the aperture 342 and into the volute 311. Animpeller 312 positioned in the pump volute 311 rotates and increases apressure head in the working fluid before the fluid passes from the pumpvolute through the opening 344 and into the inlet plenum 335.

As indicated by the arrows in FIG. 10, the working fluid can pass fromthe inlet plenum 335 and into a chamber formed between the secondrecessed region 365 in the insert 334 and the inlet manifold portion 336of the housing. From the chamber, the working fluid passes through theaperture 361.

As described above in connection with FIGS. 2, 3 and 4, the heatexchanger shown in FIGS. 7, 11, 13 and 14 can comprise a heat transferregion 324 defining a plurality of microchannel passages. The aperture361 can overlie the heat transfer region 324, and the flow of workingfluid can be distributed among the plurality of microchannel passages inthe heat sink. As with the assembly shown in FIGS. 5 and 6, a flow ofworking fluid within the microchannel can generally be an impinging flowdivided into a first portion and a second portion flowing outwardly fromthe impingement region in generally opposite directions.

In the illustrated assembly 300 (FIG. 7), the insert 334 (e.g., themembers 362 a,b,c,d) partially occupies the third recessed region 351,leaving a pair of opposed portions of the region unfilled and definingopposed exhaust manifold portions 337 overlying end regions of themicrochannels and flanking the central region adjacent the aperture 361(FIG. 11). The outwardly directed flow of coolant can exhaust from themicrochannel passages into a respective one of the exhaust manifoldportions 337. From the manifold portions 337, the working fluid passesinto the outlet plenum 338 (FIG. 11), and through the conduit 347 to theoutlet port 332.

Additional Heat Exchanger Configurations

Additional heat sink embodiments are described with reference to FIGS.13, 13A, 14, 14A, 15, 16, 17, 18A and 18B and 19. As with the heat sinkillustrated in FIG. 2 through FIG. 6, the heat sinks 320, 320′ shown inFIGS. 13 and 14 define respective heat transfer regions 324, 324′ havinga plurality of juxtaposed fins (e.g., fins 400) defining a correspondingplurality of microchannels (e.g., microchannels 404, 404′) betweenadjacent fins.

Each of the fins 400, 400′ extend from a heat spreader, or base, 326, toa respective distal end 401, 401′. Flanking grooves 322, 322′ (FIGS. 13and 14) can extend orthogonally relative to opposed outer ends of themicrochannels 404, 404′, forming a portion of an exhaust manifold. Whenincorporated in the assembly 300, the grooves 322, 322′ are generallypositioned adjacent opposed exhaust manifold portions 337.

FIG. 15 shows a typical cross-sectional view of the heat sinks 320, 320′along section line 15-15 (FIG. 13) or 15′-15′ (FIG. 14), respectively.FIGS. 16 and 17 show alternative fin configurations from the circledportion “A” of a typical heat transfer region shown in cross-section inFIG. 15.

The distal ends of the fins can have a variety of configurations, asindicated in FIGS. 16 and 17. For example, the blunt distal ends 405′are shown as being relatively flat and generally coplanar.Alternatively, the distal ends 401 are shown as being beveled, givingeach fin 400 a a comparatively shorter face and a comparatively tallerface, with a relatively sharp apex 405 positioned therebetween.

It is believed that the relatively sharp apex 405 formed by the beveleddistal ends 401 can improve transition of a flow direction (e.g., a90-degree bend) from being generally parallel to the base 326 andorthogonal to the fins 400 to a direction being generally orthogonal tothe base 326 and generally parallel to the fins. Accordingly, it issurmised that fins 400 having sharp apices 405 formed by beveled distalends can reduce head losses in the working fluid as it passes from theinsert manifold 365 to the microchannels 404 as compared to, forexample, fins 400′ having generally blunt distal ends 405′. It isbelieved that positioning the relatively taller face of a given finupstream of the relatively shorter face of the same fin (e.g., placingthe sharp apex in an upstream position relative to the respective fin),provides a relatively larger reduction in head loss than if the flowapproaches the beveled fin from an opposite direction.

The beveled distal ends 401 can be formed using any suitable techniquefor beveling thin walls. For example, such bevels can be produced whenforming the fins 400 using a skiving technique. Other, e.g, proprietary,techniques can be used to form the bevels. For example, it is believedthat the fin-forming technique employed by Wolverine Tube, Inc. can beused to produce microchannel heat sinks having beveled fins. However, itis also believed that the respective distal ends of such “raw” fins maynot be coplanar (apart from a recessed region forming a portion of atransverse groove). By incorporating the compliant insert 334, which canurge against and form a seal with uneven fins, secondary machiningoperations that would tend to dull the sharp apices 405 can beeliminated, saving costs and improving performance. Maintaining sharpapices 405 and forming a seal with the manifold insert can reduce headlosses in the coolant, while still reducing or eliminating leakagebetween adjacent microchannels 404 that might otherwise occur throughgaps that would otherwise be formed between the “raw” fins and, e.g., agenerally planar, rigid plate.

As shown in FIG. 14, a transverse groove 325 can extend transverselyrelative to the fins 400. As noted above, the aperture 361 in themanifold insert 334 can generally overlie the groove 325, defining aflow transition that hydraulically couples in parallel each of themicrochannels 404 to at least one other of the microchannels.

FIG. 19 shows a cross-sectional view of one example of such a flowtransition. The recessed region 365 defined by the insert body 360 andthe recessed groove 325 together define a substantially largercharacteristic length, e.g., hydraulic diameter, than the aperture 361does alone. For example, the recessed region 365, the aperture 361 andthe groove 325 can together define a flow transition having a hydraulicdiameter between about 150% and about 200% larger than the correspondinghydraulic diameter of the aperture 361 alone, which can provide asubstantially lower head-loss coefficient for the assembled flowtransition.

Increasing the characteristic length scale of the transition from theinlet manifold to the microchannels of the heat sink 320 can reducepressure losses in a fluid passing through the transition and increasethe flow rate of the fluid in correspondence with the pump'sperformance. The increase in fluid flow rate resulting from a lowerhead-loss coefficient can improve local heat transfer rates from thefins compared to a configuration in which the aperture 361 overlies anarray of uniform height fins. The combination of the tapered recess 365and the heat sink groove 325 (e.g., in FIG. 19A) allows the workingfluid to penetrate relatively deeper in the microchannels in a regionadjacent the aperture 361 than the fluid otherwise would in the absenceof the groove (e.g., in the case of an array of uniform height finsshown in FIG. 19A).

The groove 325 can be formed by defining a respective recess in each ofthe plurality of fins 400. The plurality of recessed regions can be sojuxtaposed as to define the groove 325.

In FIGS. 18A and 18B, the lowermost extent of each recessed groove 325a, 325 b is spaced a distance h₁ from the heat spreader 326. In otherembodiments, the lowermost extent of the recessed groove 325 issubstantially coextensive with the heat spreader 326 (i.e., h₁≤0). Insome embodiments, a ratio of a representative height h₂ of the fins tothe distance h₁ can be between about 10:1 and about 10:7, such as, forexample, between about 3:1 and about 2:1.

Although a v-shaped notch is shown in FIG. 18A, and a generallyparabolic recess is shown in FIG. 18B, other recessed grooveconfigurations are possible. For example, the groove can have agenerally hyperbolic cross-sectional shape, or a cross-section with atleast one substantially straight edge (e.g., an L-shaped recess, aflattened “V”-shaped grove as shown in FIG. 19B). As noted above, aslope of the groove 325 adjacent the manifold body can be substantiallycontinuous with a slope of a wall defining the recessed region 365 inthe manifold body 360 adjacent the groove, when the integrated assembly300 is assembled. Such a continuous slope can provide generally lowerhead losses through the transition than in transitions having adiscontinuity in wall slope (e.g., between the recess in the insert andthe groove).

Other Exemplary Embodiments

The examples described above generally concern fluidic heat transfersystems configured to cool one or more electronic components, such asintegrated circuits. Nonetheless, other applications for disclosed heattransfer systems are contemplated, together with any attendant changesin configuration of the disclosed apparatus. Incorporating theprinciples disclosed herein, it is possible to provide a wide variety ofsystems configured to transfer heat using a fluid circuit. For example,disclosed systems can be used to transfer heat to or from components ina data center, laser components, light-emitting diodes, chemicalreactions, photovoltaic cells, solar collectors, and a variety of otherindustrial, military and consumer devices now known and hereafterdeveloped.

Directions and references (e.g., up, down, top, bottom, left, right,rearward, forward, etc.) may be used to facilitate discussion of thedrawings but are not intended to be limiting. For example, certain termsmay be used such as “up,” “down,”, “upper,” “lower,” “horizontal,”“vertical,” “left,” “right,” and the like. Such terms are used, whereapplicable, to provide some clarity of description when dealing withrelative relationships, particularly with respect to the illustratedembodiments. Such terms are not, however, intended to imply absoluterelationships, positions, and/or orientations. For example, with respectto an object, an “upper” surface can become a “lower” surface simply byturning the object over. Nevertheless, it is still the same surface andthe object remains the same. As used herein, “and/or” means “and” or“or”, as well as “and” and “or.” Moreover, all patent and non-patentliterature cited herein is hereby incorporated by references in itsentirety for all purposes.

The principles described above in connection with any particular examplecan be combined with the principles described in connection with any oneor more of the other examples. Accordingly, this detailed descriptionshall not be construed in a limiting sense, and following a review ofthis disclosure, those of ordinary skill in the art will appreciate thewide variety of fluid heat exchange systems that can be devised usingthe various concepts described herein. Moreover, those of ordinary skillin the art will appreciate that the exemplary embodiments disclosedherein can be adapted to various configurations without departing fromthe disclosed principles.

The previous description of the disclosed embodiments is provided toenable any person skilled in the art to make or use the disclosedinnovations. Various modifications to those embodiments will be readilyapparent to those skilled in the art, and the generic principles definedherein may be applied to other embodiments without departing from thespirit or scope of this disclosure. Thus, the claimed inventions are notintended to be limited to the embodiments shown herein, but are to beaccorded the full scope consistent with the language of the claims,wherein reference to an element in the singular, such as by use of thearticle “a” or “an” is not intended to mean “one and only one” unlessspecifically so stated, but rather “one or more”. All structural andfunctional equivalents to the elements of the various embodimentsdescribed throughout the disclosure that are know or later come to beknown to those of ordinary skill in the art are intended to beencompassed by the elements of the claims. Moreover, nothing disclosedherein is intended to be dedicated to the public regardless of whethersuch disclosure is explicitly recited in the claims. No claim element isto be construed under the provisions of 35 USC 112, sixth paragraph,unless the element is expressly recited using the phrase “means for” or“step for”.

Thus, in view of the many possible embodiments to which the disclosedprinciples can be applied, it should be recognized that theabove-described embodiments are only examples and should not be taken aslimiting in scope. I therefore reserve all rights to the subject matterdisclosed herein, including the right to claim all that comes within thescope and spirit of the following claims, as well as all aspects of anyinnovation shown or described herein.

1. A heat exchange system comprising: a heat sink having a plurality ofjuxtaposed fins defining a corresponding plurality of microchannelsbetween adjacent fins, wherein a recessed groove extends transverselyrelative to the fins; a manifold body at least partially defining anopening generally overlying the groove. 2.-48. (canceled)